External ring clamp



FIG. 1 is a perspective view of an external ring clamp showing my new design.

FIG. 2 is a side elevational view of FIG. 1, the opposite side being a mirror image thereof.

FIG. 3 is a bottom plan view of FIG. 1; and

FIG. 4 is a right end elevational view of FIG. 1. 

The ornamental design for an external ring clamp, as shown. 